The present invention relates to an eyeglass lens securing cup for setting an eyeglass lens as a workpiece on a lens grinding machine. The invention also relates to a lens transport apparatus and method for transporting the eyeglass lens to which said cup is attached.
Machining of the periphery of an eyeglass lens with a grinder generally includes holding a workpiece lens (a lens to be machined) between two rotating shafts and machining the periphery of the lens with a grinding wheel while revolving the lens. In order to hold the lens between the rotating shafts, a securing cup is mounted on a lens surface and set on a cup holder connected to one rotating shaft. The securing cup to be mounted on a lens surface is available either as a type having a flared sucking portion or as a type which is mounted on a lens surface via a double-side adhesive pad.
In the machining of the periphery of eyeglass lens having refractive power, the lens to be machined is typically mounted on a securing cup such that its optical center and the axis of astigmatism are oriented in specified directions and the cup is then set on a cup holder in the grinder. In another method, the securing cup is mounted in a position corresponding to the geometric center of an eyeglass frame. Either method allows the lens to be machined while keeping a controlled relationship between the center of lens revolution and its optical center.
Machining of the periphery of eyeglass lens has conventionally been performed by an optician using an in-house grinder so that the lens is fitted in the eyeglass frame to be offered to a customer. Recently, with the efforts on the side of opticians toward rationalization of their business operations and the advances in communication technology, it is becoming increasingly popular to process a number of lenses in a large machining center at the request of many opticians.
Even in such centralized operations, the existing machining centers rely upon individual operators to set lenses on grinders, thus requiring much labor and time in lens transport and mounting procedures. Certain kinds of lenses (e.g., dummy lenses and sunglasses) are machined as they are secured by surface suction for automatic transport. However, this approach of transport is not suitable for the eyeglass lens having refractive power because of the need to take its optical center and axial angle into account and due to the variability of lens geometry.